title: The impact of acute hypothyroidism on lipid levels in athyreotic patients.
abstract: BACKGROUND
  We investigated the effect of acute hypothyroidism on lipid concentrations especially on high density lipoprotein (HDL-cholesterol) level in athyroatic patients.
  
  
  METHODS
  Thirty-one patients, with a history of differentiated thyroid carcinoma and total thyroidectomy, who were candidates of radioiodine therapy, enrolled in the study. Their lipid profiles and serum thyrotropin stimulating hormone (TSH) levels were measured before and two-to-six weeks after thyroid hormone withdrawal. The lipid concentrations were compared with the paired t test and serum TSH using the Wilcoxon singed rank test. P values < 0.05 were considered statistically significant.
  
  
  RESULTS
  The median of TSH concentration was 0.06 mU / liter on thyroid hormone suppressive therapy and 102 mU / liter at the thyroid hormone withdrawal phase (P < 0.0001). The serum concentrations of all lipids were significantly increased after withdrawal (P < 0.0001). The mean (SD) of the HDL-cholesterol concentration rose from 44 ± 9 mg / dL to 58 ± 17 mg / dL. The levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglyceride increased by 58, 75, 30, and 59%, respectively, during acute hypothyroidism.
  
  
  CONCLUSIONS
  The present study showed that thyroid hormone withdrawal altered the lipid concentrations significantly, in a short period of time. The levels of both atherogenic (LDL-cholesterol) and cardioprotective (HDL-cholesterol) particles increased concurrently. Their clinical importance should be investigated in future.
authors.affiliation: Isfahan Endocrine and Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Rezvan
authors.initials: R
authors.lastname: Salehidoost
authors.forename: Ashraf
authors.initials: A
authors.lastname: Aminorroaya
authors.forename: Bijan
authors.initials: B
authors.lastname: Iraj
authors.forename: Massoud
authors.initials: M
authors.lastname: Amini
keywords: Cholesterol-HDL; hypothyroidism; lipid metabolism; thyroid hormones; thyroid neoplasms